Speed governor



J. A. MARTIN SPEED GOVERNOR Aug. 30, 1938.

Filed July 26, 1955 Patented Aug. 30, 1938 PATENTv OFFICE SPEED* GOVERNOR John A. Martin,

Application July 26,

1 Claim.

My invention relates to speed governors for automobiles, and more specifically to speed governorsof the type which can be associated with the conventional automobile speedometer. A further object of my invention is to produce a device of this kind which, while adjustable by authorized persons, can not be readily tampered with to change its adjustment or to alter the control it exercises. Still another object of my l invention is to produce a speed governor in the operation of which the operator of the vehicle will be warned before the maximum predetermined speed limit is attained in order thereby to deter the operator from attempting some maneuver which the speed-limiting operation of the device would prevent. An additional object of my invention is to provide means whereby an indication will be given if the automobile is, as the result of unauthorized tampering with the speed-control mechanism, driven at a speed materially above that for which the speed-governing device is set.

In carrying out my invention, I associate with a speedometer having a movable speed-indicating hand, a rotatable ring mounted concentric with the hand; and from this ring I support three normally separated electrical contacts so arranged that in the movement of the hand they will be brought successively into engagement to complete various electrical circuits by means of which the functions performed by the device are elected. The angular position of the ring relative to the speedometer-dial determines the maximum speed, and the position of the ring is conveniently made adjustable through the use of adjusting mechanism which is normally locked. Conveniently, the adjustable ring is mounted within an extension of the speedometer housing which is locked to the speedometer housing, preferably by the same means employed to lock the adjusting mechanism.

The accompanying drawing illustrates my invention: Fig. 1 is a front elevation of a speedometer to which my invention has been applied, with parts thereof broken away and with electric connections indicated largely diagrammatically; Fig. 2 is a side elevation of the speedometer with parts thereof broken away and shown in section on the line 2-2 of Fig. 1; and Figs. 3 and 4 are diagrammatic illustrations of alternative means which may be employed in controlling the engine to limit its speed.

The speedometer illustrated in the drawing has a casing I0 which encloses any satisfactory form of speed-responsive mechanism controlling Indianapolis, Ind.

1935, Serial No. 33,298

the angular position of an indicating hand II relative to a stationary graduated dial I2. For the purpose of providing protection for the hand II and dial I2 and in order to provide an enclosure for those portions of my invention which are directly associated with the speedometer, I provide for the casing I0 a forwardly projecting extension I3 closed at its outer end by a disk of glass I4 or other suitable transparent material.

Within the extension I3 I mount for rotational adjustment a ring I6 of insulating material in the outer face of which are embodied three concentric colleotor rings I'I, I8, and I9 with which there respectively co-operate brushes 2|, 22 and 23. v

Supported from the ring I6 and connected respeotively to the three collector rings I1, I8, and I9 are three spring-contact members 25, 25, and 2'I. These contact members project radially inwardly from the ring I6 and are normally disengaged from each other. That one of the spring contacts 25, 26, and 2l which is nearest to the zero position of the hand II, here shown as the contact 25, is arranged to be engaged by the hand II in its movement and to be forced into Contact with the intermediate spring-contact 25 and then to force such intermediate contact into engagement with the third spring contact 2'I. Conveniently, the outer end of the spring-contact 26 is provided with a rearward extension 28 disposed in the path of movement of a block 29 of insulating material carried by the hand I I.

The apparatus which it is the object of my invention to control may take different forms and is operated through the closure of electrical circuits eiected by engagement of the contacts 25-26-21. As previously indicated, I prefer to incorporate in the device embodying my invention a warning signal which will indicate to the driver that any material increase in speed is impossible. Such warning signal may be in the form of a lamp, and may be mounted within the casing-extension I3. As shown, the lamp 32 is mounted in a bridge 3| secured to the inner face of the casing-extension I3 near the bottom thereof. Other apparatus shown in the drawing and adapted to be operated through closing of electrical circuit by engagement of the contacts 25--25-21 includes a buzzer 33 adapted to be operated simultaneously with the lamp` and a relay 34 which, when energized, renders the ignition system of the engine inoperative.

In the drawing, I have indicated a battery 35 011 'terminal of which is grounded and the other terminal of which is connected to a bolt 36 extending through the wall of the casing-extension I3. The bolt 36 may be employed to hold one leg of the bridge 3| in place, but the bolt is insulated from the bridge and from the casing-extension, and carries on its inner end the brush 23 engaging the outermost collector ring I9. The brush 22, which engages the intermediate collector ring I8, is mounted upon the bridge 3 I. The brush 2 I, which engages the innermost collector ring l1, is carried upon the inner end of a post 31 which is insulated from the casing and from the bridge. A bolt 38, electrically connected to the bridge 3| but insulated from the casing may co-operate with the bolt 36 in holding the bridge 3l in place.

One terminal of the lamp 32 is connected with the bridge 3|, while the other terminal is grounded. One terminal of the buzzer 33 is connected to the bolt 36 and the other terminal is grounded, while the winding of the relay 34 is connected, by a wire 39, between the post 31 and ground. As indicated in the drawing, the relay 34 is so arranged that when energized it will render inoperative the engine ignition system, as by opening the primary side thereof.

By adjusting the angular position of the ring I6 the position of the contacts 25--26--21 maybe varied to vary in turn the speed at which the governor operates to stop the engine.

Because the hand II must exercise an appreciable, though slight, force in displacing the `contact members 25` and 26 it is essential that the speed-responsive mechanism in the casing I0 be of a type capable of exerting such a force. I have found any of the common types .of centrifugal-force-responsive mechanisms to be suitable.

Preferably, means are provided for adjusting the angular position of the ring IB from without the casing. To this end, the ring may be provided with a circumferentially extending series of gear teeth 40 meshing with a pinion 4I rotatably mounted within a housing 42 carried by the flange I3. As shown in the drawing, the pinion 4I has rigid with it a rearwardly extending stub shaft 43 rotatably supported in a journal 44 which is rigid with the housing 42. On its front face, the pinion 4I has a forwardly extending, non-circular boss 45 which is co-axial with the pinion and which is adapted to receive a key by means of which the pinion may be rotated. The front of the housing 42 is closed by a cover 46 which has a central opening for the passage of the adjusting key.

In order to permit access to the working parts of the device, the cover-glass I4 is preferably not mounted directly upon the flange I3, but instead is mounted in a ring 5D whichtelescopically receives the ange I3 and which is adapted to be held in place thereon as `by the bayonet-lock 5 shown in Fig. 2.

As is clear from Fig. 2, the speedometer casing IU and the flange I3 rigid with it are supported from the rear in line with an opening in the instrument board 52 of the automobile, and the ring 5I) is arranged to pass through such opening into association with the flange I3. By rotating the ring slightly from the position shown in Fig. 2, the bayonet-lock 5I may be released and the ring withdrawn from the opening in the instrument board to expose the working parts of the device.

To prevent unauthorized changes in adjustments, I may mount in the instrument board 52 a lock 55 having a rotatable element 56 with which there is rigid an arm 51 adapted to be swung into and out of alinement with the central opening in the housing-cover 46. As shown in full lines in Fig. l, the arm 51 is disposed over the opening in the housing-cover 46 to prevent insertion of the key which is necessary to rotate the pinion 42 and change the position of the ring I6. By operation of the lock 55, however, the arm 51 can be swung to the dotted-line position shown in Fig. 1 in which it uncovers the central opening in the cover 46 and makes it possible to insert the key, rotate the pinion 42, and change the setting of the ring I6.

In addition to its function in preventing access to the pinion 42, the arm 51 may also serve as a latch preventing unauthorized removal of the ring 5I). For this purpose, the arm 51 may extend beyond the axis of the pinion 42 and may have its extreme outer end 58 bent inwardly to pass through holes of the ring 50 and flange I3, which holes are in alinement when the bayonet-lock 5I is locked.

Assuming that the ring I5 has been so adjusted as to adjust the contact members 25-26-21 in the prop-er position to effect the desired speed control, the operation of the device will be obvious. As the vehicle speed increases, the speedometer hand il may swing in a clockwise direction over the dial l2. As this movement of the hand continues, the block of insulating material 29 will eventually strike the projection 2B on the contact member 25 and Will force such contact i member into engagement with the middle contact member 25. rllhis closes the circuit from the ungrounded terminal o1 the battery through the bolt 36, brush 23, collector ring- I9, contact members 25. and 25, collector ring I8,'brusl1 22, and the lamp 32 to ground. The resulting supply of current to the lamp causes it to light and warns the driver that the maximum speed is about to be attained. When the lamp 32 is lighted, the buzzer 33 or other warning signal in` parallel with it is also actuated. Any continued increase in vehicle speed forces the middle contact 25 into engagement with the contact 21 thus completing the supply of battery current from the collector ring I9 through the contact members 25 and 21, collector ring I1, post 31, and wire 39 to the relay 34. When the relay 34 is energized, it operates as above set forth to open the primary side of the ignition system of the engine, thus rendering the engine inoperative and causing a decrease in the vehicle sneed.

As the speed-governing function is exercised in accordance with the speed of the automobile rather than the speed of the engine, my device imposes no undue restriction on available power when the car is not running in high gear.

It is to be noted that the speedometer hand I I, in forcing the contacts 25 and 21 together, has to overcome the elastic resistance of both the contact members 25 and 26, which exert on the hand a force tending Vto move it in a counterclockwise direction. As soon, therefore, as the vehicle speed decreases as the result of the opening of the ignition system, the contact members 25 and 26 force the hand II in a counterclockwise direction with the result that the contact members 25 and 21 are immediately separated and the relay 34 de-energized to close the primary side of the engine ignition system. As a result, the engine again becomes operative with but a slight delay.

The function of the resilient contact members 25 and 25 in immediately de-energizing the relay 34 is of considerable importance; for it prevents a quantity of explosive gases from collecting in the muiiler and exhaust pipe of the engine Where their subsequent explosion might result in considerable damage.

The contact member 26 and its extension 28 are preferably so proportioned as to yield and permit the hand Il to pass beyond them if the force exerted by the hand becomes great enough. Should the operator, by tampering with the electrical connections or otherwise, be enabled to drive the automobile at a speed beyond that for which the ring I6 is set, the hand Il would force the extension 28 aside and pass beyond it'; Upon a later deceleration of the automobile the extension 28 would engage the hand and prevent its return to zero position, thus giving an indication that the automobile had been operated at excessive speed.

It is not essential that the control which my governor exerts on the engine be obtained through opening of the ignition circuit as shown in Fig. 1. Thus, in Fig. 3, I have shown the mixture-induction conduit of the engine as provided with an auxiliary throttle 6i connected to the armature of a solenoid 62 which is connected between the wire 39 and ground. In the operation of this device, when the speed of the vehicle has reached the point such as to cause the hand il to force' the contacts 25 and 21 into engagement with each other, the solenoid 62 will be energized, exactly as the relay 34 will be energized in the arrangement shown in Fig. 1, and the resultant movement of the armature will close the throttle 6| to decrease the speed of the engine and of the vehicle.

Another arrangement is illustrated in Fig. 4 Where the customary throttle 65 of the enginecarburetor 66 is operated by an accelerator pedal 61. The accelerator pedal is rigid with a shaft 68 which carries an arm 69 connected by a link 10 with the throttle B5. The shaft 68 also has rigid with it a toothed sector 1l co-operating with which is a paWl 12 which is normally free from engagement with the teeth of the sector but which can be moved into engagement therewith by energization of the solenoid 13 connected between the wire 38 and ground. With such a device, when the hand Il forces the contacts 25 and 21 together, the resultant energizing of the solenoid 13 forces the pawl 12 into engagement with the teeth of the sector 1l .and prevents such movement of the shaft 68 as it is necessary to further open the throttle 65.

Not only can my advice be utilized as a speed governor; but by rotating the ring I6 to bring the contacts 25--26-21 close to the zero position on the dial I2, the device becomes an effective deterrent to theft of an automobile on which it is mounted.

I claim as my invention:

In a device of the type described, a scale, a hand movable thereover, speed-responsive means for moving said hand, a pair of co-operating electrical contacts, one of said contacts having a portion projecting into the path of movement of said hand, a support carrying said contacts and adjustable along the path of movement of said hand, a casing enclosing said contacts, said hand, and said support, said casing having a removable cover, an adjusting device for moving said support, and a lock for said adjusting device, said lock and cover having co-operating provisions for preventing removal of said cover when said lcc-k is locked.

J OHN A. MARTIN. 

